Topic: Splitting the carbs

[JDrider]

1975 cb550k1
I have located a leak when doing a pressure test after a carb rebuild.
That the fuel line T between the carbs were leaking air.

How much of a pain is it to split the 1 and 4 carb off to do this?

Thanks,

[bryanj]

You cant just get 1 and 4 off, you have to loosen all of them, for O ring kits look up Nurse Julie

[MauiK3]

+1
If one leaks, do all.

[JDrider]

Yes, I quickly found that out. Lol.
Everything is coming apart now.

[JDrider]

This video shows a succesful reassembling, from 00:20 on. The language is German, but the images speak for them selves. Tip: I would not use tube clips where the fuelline connects to the T-joint. The lines will never come loose (40 years experience here ) and if you fit them wrongly, they will be in the way later on when you need to access the airscrews.

video courtesy Gruzzel

Where is a good source for correct fuel lines?

[Deltarider]

No idea. You have to excuse me: I live on another continent. Make sure their dimensions are as I have posted before.

[JDrider]

Ok, thanks

[JDrider]

No idea. You have to excuse me: I live on another continent. Make sure their dimensions are as I have posted before.

I had purchased this a few months ago, so I think this will work.

https://www.ebay.com/itm/143723776639

I will cut the lengths you mention for the newer style petcock on my 1975 cb550k1.

[Deltarider]

Yes. BTW, inside ⌀ 5.5mm was used on old VWs like the beetle and early transporters.
Tip: many owners complain about the throttle operation which needs quite some force by your wrist, due to the stiff central spring. Someone in the UK suggested to add a ring (see pic below).
After reassembly you will need to resync. You could try what I have suggested in previous posts. You could start with say 4 identical popsicle sticks, just to see if it in principle works.

[JDrider]

I planned on bench syncing once I’m reassembled.
I don’t get the popsicle stick reference.

[Deltarider]

http://forums.sohc4.net/index.php/topic,193284.msg2255748.html#msg2255748
The popsickle sticks will not be accurate, because they're round and so will roll. But they're cheap enough to test the principle. Maybe it could also be done air intake side instead of engine side. But then you would need thicker ones. Steel balls will also work but it can be time consuming.
Can you post an overview pic of what you have disassembled. I mean the desmodromic, the shaft etc. I may have a tip for a correct basic setting.

[JDrider]

Ah, I see.
I was planning to do the drill bit method.

[Deltarider]

I was planning to do the drill bit method.

Not my favourite method.
Doing it engine side, has always worked for me. You may want to unhook that central spring.
I've used a small allen key's long leg as a feeler gauge which I slided carefully under that very little 'cut out' in the slide engine side. This after I turned the big idle knob for an aperture that suits the allen key. After the syncing you turn that knob back again. You have to concentrate well and take your time. When finished, have a coffee and then check once more. I must have done it three times now. When checked afterwards with vacuum gauges, it turned out I had managed to limit the difference within 2 cm Hg, which not only is well within factory specs, but also provides a good driveability. 

[JDrider]

Update:
Everything went well.
Put new o rings on the fuel line T
Cut the new fuel lines to proper length
Installed new fuel lines.
Re-assembled the carbs.

Did a pressure test with the mityvac and it is holding pressure!

I will do a bench sync later

Thank you for all your help!